This invention relates generally to turbomachinery, and specifically to turbine rotor vibrations. In particular, the invention concerns vibration signal processing for trim balancing and vibration reduction in gas turbine engines
Gas turbine engines (or combustion turbines) are built around a power core made up of a compressor, combustor and turbine, arranged in flow series with an upstream inlet and downstream exhaust. The compressor compresses air from the inlet, which is mixed with fuel in the combustor and ignited to generate hot combustion gas. The turbine extracts energy from the expanding combustion gas, and drives the compressor via a common shaft. Energy is delivered in the form of rotational energy in the shaft, reactive thrust from the exhaust, or both.
Gas turbine engines provide efficient, reliable power for a wide range of applications, including aviation and industrial power generation. Small-scale engines including auxiliary power units typically utilize a one-spool design, with co-rotating compressor and turbine sections. Larger-scale jet engines and industrial gas turbines (IGTs) are generally arranged into a number of coaxially nested spools, which operate at different pressures and temperatures, and rotate at different speeds.
Individual compressor and turbine sections in each spool are subdivided into a number of stages, which are formed of alternating rows of rotor blade and stator vane airfoils. The airfoils are shaped to turn, accelerate and compress the working fluid flow, and to generate lift for conversion to rotational energy in the turbine.
Ground-based industrial gas turbines can be quite large, utilizing complex spooling systems for increased efficiency. Power is delivered via an output shaft connected to an electrical generator, or other mechanical load. Industrial turbines can also be configured for combined-cycle operation, in which additional energy is extracted from the exhaust stream, for example using a low pressure steam turbine.
Aviation applications include turbojet, turbofan, turboprop and turboshaft engines. In turbojet engines, thrust is generated primarily from the exhaust. Modern fixed-wing aircraft typically employ turbofan and turboprop engines, in which the low pressure spool is coupled to a propulsion fan or propeller. Turboshaft engines are used on rotary-wing aircraft, including helicopters.
Turbofan engines are commonly divided into high and low bypass designs. High bypass turbofans generate thrust primarily from the fan, which drives airflow through a bypass duct oriented around the engine core. This configuration is common on commercial aircraft and military transports, where noise and fuel efficiency are primary concerns. Low bypass turbofans generate proportionally more thrust from the exhaust flow, providing greater specific thrust for use on supersonic fighters and other high-performance aircraft. Unducted (open rotor) turbofans and ducted turboprop designs are also known, including counter-rotating and aft-mounted configurations.
Gas turbine engine performance depends on precise control of the turbine and compressor rotor speeds. When the rotors are out of balance, vibrations result, reducing engine efficiency and service life. To address these effects, vibration sensors are used to detect rotor imbalances, with vibration signal processors designed to generate effective trim balance solutions for improved performance and service life.